Staggered pilot placement

ABSTRACT

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be configured to receive a plurality of combined signals. Each combined signal may be on a tone of a plurality of tones. The apparatus may be configured to determine a first pilot signal on a first tone of the plurality of tones. The apparatus may be configured to generate an interference-reduced signal for the first tone by canceling the determined first pilot signal from a first combined signal on the first tone.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of U.S. Provisional Application Ser.No. 62/269,915, entitled “STAGGERED PILOT PLACEMENT” and filed on Dec.18, 2015, which is expressly incorporated by reference herein in itsentirety.

BACKGROUND

Field

The present disclosure relates generally to communication systems, andmore particularly, to techniques of staggered pilot placement at a userequipment (UE) that may be used to enable interference cancelation at anevolved Node B (eNodeB) or another type of base station.

Background

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources (e.g., bandwidth,transmit power). Examples of such multiple-access technologies includecode division multiple access (CDMA) systems, time division multipleaccess (TDMA) systems, frequency division multiple access (FDMA)systems, orthogonal frequency division multiple access (OFDMA) systems,single-carrier frequency division multiple access (SC-FDMA) systems, andtime division synchronous code division multiple access (TD-SCDMA)systems.

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example telecommunication standardis Long Term Evolution (LTE). LTE is a set of enhancements to theUniversal Mobile Telecommunications System (UMTS) mobile standardpromulgated by Third Generation Partnership Project (3GPP). LTE isdesigned to better support mobile broadband Internet access by improvingspectral efficiency, lowering costs, improving services, making use ofnew spectrum, and better integrating with other open standards usingOFDMA on the downlink (DL), SC-FDMA on the uplink (UL), andmultiple-input multiple-output (MIMO) antenna technology. However, asthe demand for mobile broadband access continues to increase, thereexists a need for further improvements in LTE technology. Preferably,these improvements should be applicable to other multi-accesstechnologies and the telecommunication standards that employ thesetechnologies.

SUMMARY

In an aspect of the disclosure, a method, a computer-readable medium,and an apparatus are provided. The apparatus may be configured toreceive a plurality of combined signals. Each combined signal may be ona tone of a plurality of tones. Each combined signal may include a firstsymbol of a first plurality of symbols from a first UE and a secondsymbol of a second plurality of symbols from a second UE. The firstplurality of symbols may include at least one first pilot symbol and atleast one first data symbol, and the second plurality of symbols mayinclude at least one second pilot symbol and at least one second datasymbol. Each of the at least one first pilot symbol may be on a tonethat carries one of the at least one second data symbol. The apparatusmay be configured to determine a first pilot signal on a first tone ofthe plurality of tones. The first tone may carry a respective one of theat least one first pilot symbol and a respective one of the at least onesecond data symbol. The first pilot signal may be determined based on achannel element associated with the first tone and the respective one ofthe at least one first pilot symbol on the first tone. The apparatus maybe configured to generate an interference-reduced signal for the firsttone by canceling the determined first pilot signal from a firstcombined signal on the first tone.

In another aspect, an apparatus is provided. The apparatus may includemeans for receiving a plurality of combined signals. Each combinedsignal may be on a tone of a plurality of tones. Each combined signalmay include a first symbol of a first plurality of symbols from a firstUE and a second symbol of a second plurality of symbols from a secondUE. The first plurality of symbols may include at least one first pilotsymbol and at least one first data symbol, and the second plurality ofsymbols may include at least one second pilot symbol and at least onesecond data symbol. Each of the at least one first pilot symbol may beon a tone that carries one of the at least one second data symbol. Theapparatus may include means for determining a first pilot signal on afirst tone of the plurality of tones. The first tone may carry arespective one of the at least one first pilot symbol and a respectiveone of the at least one second data symbol. The first pilot signal maybe determined based on a channel element associated with the first toneand the respective one of the at least one first pilot symbol on thefirst tone. The apparatus may include means for generating aninterference-reduced signal for the first tone by canceling thedetermined first pilot signal from a first combined signal on the firsttone. The apparatus may include mean for determining a second pilotsignal on a second tone of the plurality of tones. The second tone maycarry a respective one of the at least one second pilot symbol and arespective one of the at least one first data symbol. The second pilotsignal may be determined based on a second channel element associatedwith the second tone and the respective one of the at least one secondpilot symbol on the second tone. The apparatus may include means forgenerating a second interference-reduced signal for the second tone bycanceling the determined second pilot signal from a second combinedsignal on the second tone. The apparatus may include means fordemodulating the interference-reduced signal, the secondinterference-reduced signal, and remaining signals on a subset of tonesof the plurality of tones to decode the at least one first data symboland the at least one second data symbol. In an aspect, a first set ofperiodic pilot signals from the first UE and a second set of periodicpilot signals from the second UE are shifted by a cyclic shift. Inanother configuration, the apparatus may include means for providing acyclic shift to the first UE. In another configuration, the apparatusmay include means for de-interleaving the plurality of combined signalsto determine a first set of pilot signals from the first UE, first andsecond code blocks from the first UE, a second set of pilot signals fromthe second UE, and third and fourth code blocks from the second UE. Inanother aspect, the first set of pilot signals may correspond to a firstnumber tones, and the first number tones may be equal to half a secondnumber of tones in the third code block. In another aspect, the firstset of pilot signals from the first UE may overlap with the third codeblock from the second UE, and the second set of pilot signals from thesecond UE may overlap with the second code block from the first UE. Inanother configuration, the apparatus may include means for performingsuccessive decoding after deinterleaving the plurality of combinedsignals. In another configuration, the means for successive decoding maybe configured to decode the third code block by canceling the first setof pilot signals from the third code block, to decode the first codeblock by canceling the third code block from the first code block, todecode the fourth code block by canceling the first code block from thefourth code block, and to decode the second code block by canceling thefourth code block from the second code block.

In another aspect, a computer-readable medium storing computerexecutable code is provided. The computer-readable medium may includecode to receive a plurality of combined signals. Each combined signalmay be on a tone of a plurality of tones. Each combined signal mayinclude a first symbol of a first plurality of symbols from a first UEand a second symbol of a second plurality of symbols from a second UE.The first plurality of symbols may include at least one first pilotsymbol and at least one first data symbol, and the second plurality ofsymbols may include at least one second pilot symbol and at least onesecond data symbol. Each of the at least one first pilot symbol may beon a tone that carries one of the at least one second data symbol. Thecomputer-readable medium may include code to determine a first pilotsignal on a first tone of the plurality of tones. The first tone maycarry a respective one of the at least one first pilot symbol and arespective one of the at least one second data symbol. The first pilotsignal may be determined based on a channel element associated with thefirst tone and the respective one of the at least one first pilot symbolon the first tone. The computer-readable medium may include code togenerate an interference-reduced signal for the first tone by cancelingthe determined first pilot signal from a first combined signal on thefirst tone.

In another aspect of the disclosure, a method, a computer-readablemedium, and an apparatus are provided. The apparatus may be configuredto map, at a first UE, a first set of pilot symbols and a first set ofdata symbols to a plurality of tones. Each pilot symbol in the first setof pilot symbols may be mapped on a tone that is used by a second UE tocarry a data symbol. The apparatus may be configured to provide thefirst set of pilot symbols and the first set of data symbols fortransmission over the plurality of tones.

In another aspect, an apparatus is provided. The apparatus may includemeans for mapping, at a first UE, a first set of pilot symbols and afirst set of data symbols to a plurality of tones. Each pilot symbol inthe first set of pilot symbols may be mapped on a tone that is used by asecond UE to carry a data symbol. The apparatus may include means forproviding the first set of pilot symbols and the first set of datasymbols for transmission over the plurality of tones. In another aspect,a data symbol in the first set of data symbols may be mapped on a tonethat is used by the second UE to carry a pilot symbol. In anotheraspect, the first set of pilot symbols may be transmitted on tonesshifted by a cyclic shift from a second set of pilot symbols that isconcurrently transmitted by the second UE. In another configuration, theapparatus may include means for receiving the cyclic shift forstaggering the first set of pilot symbols from a base station. Inanother aspect, the cyclic shift for staggering the first set of pilotsymbols is randomly selected from a set of cyclic shift values based onan identifier associated with the first UE. In another aspect, the firstset of data symbols may be associated with a same code block.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a network architecture.

FIG. 2 is a diagram illustrating an example of an access network.

FIG. 3 is a diagram illustrating an example of a DL frame structure inLTE.

FIG. 4 is a diagram illustrating an example of an UL frame structure inLTE.

FIG. 5 is a diagram illustrating an example of a radio protocolarchitecture for the user and control planes.

FIG. 6 is a diagram illustrating an example of an evolved Node B anduser equipment in an access network.

FIG. 7 is a diagram illustrating communication between an eNodeB and twoUEs.

FIG. 8 is a diagram illustrating communication between an eNodeB and twoUEs.

FIG. 9 is a diagram illustrating demodulation and decoding procedures atan eNodeB.

FIG. 10 is a diagram illustrating procedures of mapping pilot symbolsand data symbols at a UE.

FIG. 11 is a diagram illustrating demodulation and decoding proceduresat an eNodeB.

FIG. 12 is a flow chart of a method (process) for demodulation.

FIG. 13 is a flow chart of a method (process) for mapping pilot symbolsand data symbols on multiple tones.

FIG. 14 is a conceptual data flow diagram illustrating the data flowbetween different means/components in an exemplary apparatus.

FIG. 15 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system.

FIG. 16 is a conceptual data flow diagram illustrating the data flowbetween different means/components in an exemplary apparatus.

FIG. 17 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented withreference to various apparatus and methods. These apparatus and methodswill be described in the following detailed description and illustratedin the accompanying drawings by various blocks, components, circuits,steps, processes, algorithms, etc. (collectively referred to as“elements”). These elements may be implemented using electronichardware, computer software, or any combination thereof. Whether suchelements are implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem.

By way of example, an element, or any portion of an element, or anycombination of elements may be implemented with a “processing system”that includes one or more processors. Examples of processors includemicroprocessors, microcontrollers, digital signal processors (DSPs),field programmable gate arrays (FPGAs), programmable logic devices(PLDs), state machines, gated logic, discrete hardware circuits, andother suitable hardware configured to perform the various functionalitydescribed throughout this disclosure. One or more processors in theprocessing system may execute software. Software shall be construedbroadly to mean instructions, instruction sets, code, code segments,program code, programs, subprograms, software components, applications,software applications, software packages, routines, subroutines,objects, executables, threads of execution, procedures, functions, etc.,whether referred to as software, firmware, middleware, microcode,hardware description language, or otherwise.

Accordingly, in one or more exemplary embodiments, the functionsdescribed may be implemented in hardware, software, firmware, or anycombination thereof. If implemented in software, the functions may bestored on or encoded as one or more instructions or code on acomputer-readable medium. Computer-readable media includes computerstorage media. Storage media may be any available media that can beaccessed by a computer. By way of example, and not limitation, suchcomputer-readable media can comprise a random-access memory (RAM), aread-only memory (ROM), an electrically erasable programmable ROM(EEPROM), compact disk ROM (CD-ROM) or other optical disk storage,magnetic disk storage or other magnetic storage devices, combinations ofthe aforementioned types of computer-readable media, or any other mediumthat can be used to store computer executable code in the form ofinstructions or data structures that can be accessed by a computer.

FIG. 1 is a diagram illustrating an LTE network architecture 100. TheLTE network architecture 100 may be referred to as an Evolved PacketSystem (EPS) 100. The EPS 100 may include one or more user equipment(UE) 102, an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN)104, an Evolved Packet Core (EPC) 110, and an Operator's InternetProtocol (IP) Services 122. The EPS can interconnect with other accessnetworks, but for simplicity those entities/interfaces are not shown. Asshown, the EPS provides packet-switched services, however, as thoseskilled in the art will readily appreciate, the various conceptspresented throughout this disclosure may be extended to networksproviding circuit-switched services.

The E-UTRAN includes the evolved Node B (eNB) 106 and other eNBs 108,and may include a Multicast Coordination Entity (MCE) 128. The eNB 106provides user and control planes protocol terminations toward the UE102. The eNB 106 may be connected to the other eNBs 108 via a backhaul(e.g., an X2 interface). The MCE 128 allocates time/frequency radioresources for evolved Multimedia Broadcast Multicast Service (MBMS)(eMBMS), and determines the radio configuration (e.g., a modulation andcoding scheme (MCS)) for the eMBMS. The MCE 128 may be a separate entityor part of the eNB 106. The eNB 106 may also be referred to as a basestation, a Node B, an access point, a base transceiver station, a radiobase station, a radio transceiver, a transceiver function, a basicservice set (BSS), an extended service set (ESS), or some other suitableterminology. The eNB 106 provides an access point to the EPC 110 for aUE 102. Examples of UEs 102 include a cellular phone, a smart phone, asession initiation protocol (SIP) phone, a laptop, a personal digitalassistant (PDA), a satellite radio, a global positioning system, amultimedia device, a video device, a digital audio player (e.g., MP3player), a camera, a game console, a tablet, or any other similarfunctioning device. The UE 102 may also be referred to by those skilledin the art as a mobile station, a subscriber station, a mobile unit, asubscriber unit, a wireless unit, a remote unit, a mobile device, awireless device, a wireless communications device, a remote device, amobile subscriber station, an access terminal, a mobile terminal, awireless terminal, a remote terminal, a handset, a user agent, a mobileclient, a client, or some other suitable terminology.

The eNB 106 is connected to the EPC 110. The EPC 110 may include aMobility Management Entity (MME) 112, a Home Subscriber Server (HSS)120, other MMES 114, a Serving Gateway 116, a Multimedia BroadcastMulticast Service (MBMS) Gateway 124, a Broadcast Multicast ServiceCenter (BM-SC) 126, and a Packet Data Network (PDN) Gateway 118. TheMIME 112 is the control node that processes the signaling between the UE102 and the EPC 110. Generally, the MME 112 provides bearer andconnection management. All user IP packets are transferred through theServing Gateway 116, which itself is connected to the PDN Gateway 118.The PDN Gateway 118 provides UE IP address allocation as well as otherfunctions. The PDN Gateway 118 and the BM-SC 126 are connected to the IPServices 122. The IP Services 122 may include the Internet, an intranet,an IP Multimedia Subsystem (IMS), a PS Streaming Service (PSS), and/orother IP services. The BM-SC 126 may provide functions for MBMS userservice provisioning and delivery. The BM-SC 126 may serve as an entrypoint for content provider MBMS transmission, may be used to authorizeand initiate MBMS Bearer Services within a public land mobile network(PLMN), and may be used to schedule and deliver MBMS transmissions. TheMBMS Gateway 124 may be used to distribute MBMS traffic to the eNBs(e.g., 106, 108) belonging to a Multicast Broadcast Single FrequencyNetwork (MBSFN) area broadcasting a particular service, and may beresponsible for session management (start/stop) and for collecting eMBMSrelated charging information.

FIG. 2 is a diagram illustrating an example of an access network 200 inan LTE network architecture. In this example, the access network 200 isdivided into a number of cellular regions (cells) 202. One or more lowerpower class eNBs 208 may have cellular regions 210 that overlap with oneor more of the cells 202. The lower power class eNB 208 may be a femtocell (e.g., home eNB (HeNB)), pico cell, micro cell, or remote radiohead (RRH). The macro eNBs 204 are each assigned to a respective cell202 and are configured to provide an access point to the EPC 110 for allthe UEs 206 in the cells 202. There is no centralized controller in thisexample of an access network 200, but a centralized controller may beused in alternative configurations. The eNBs 204 are responsible for allradio related functions including radio bearer control, admissioncontrol, mobility control, scheduling, security, and connectivity to theserving gateway 116. An eNB may support one or multiple (e.g., three)cells (also referred to as a sectors). The term “cell” can refer to thesmallest coverage area of an eNB and/or an eNB subsystem serving aparticular coverage area. Further, the terms “eNB,” “base station,” and“cell” may be used interchangeably herein.

The modulation and multiple access scheme employed by the access network200 may vary depending on the particular telecommunications standardbeing deployed. In LTE applications, OFDM is used on the DL and SC-FDMAis used on the UL to support both frequency division duplex (FDD) andtime division duplex (TDD). As those skilled in the art will readilyappreciate from the detailed description to follow, the various conceptspresented herein are well suited for LTE applications. However, theseconcepts may be readily extended to other telecommunication standardsemploying other modulation and multiple access techniques. By way ofexample, these concepts may be extended to Evolution-Data Optimized(EV-DO) or Ultra Mobile Broadband (UMB). EV-DO and UMB are air interfacestandards promulgated by the 3rd Generation Partnership Project 2(3GPP2) as part of the CDMA2000 family of standards and employs CDMA toprovide broadband Internet access to mobile stations. These concepts mayalso be extended to Universal Terrestrial Radio Access (UTRA) employingWideband-CDMA (W-CDMA) and other variants of CDMA, such as TD-SCDMA;Global System for Mobile Communications (GSM) employing TDMA; andEvolved UTRA (E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE802.20, and Flash-OFDM employing OFDMA. UTRA, E-UTRA, UMTS, LTE and GSMare described in documents from the 3GPP organization. CDMA2000 and UMBare described in documents from the 3GPP2 organization. The actualwireless communication standard and the multiple access technologyemployed will depend on the specific application and the overall designconstraints imposed on the system.

The eNBs 204 may have multiple antennas supporting MIMO technology. Theuse of MIMO technology enables the eNBs 204 to exploit the spatialdomain to support spatial multiplexing, beamforming, and transmitdiversity. Spatial multiplexing may be used to transmit differentstreams of data simultaneously on the same frequency. The data streamsmay be transmitted to a single UE 206 to increase the data rate or tomultiple UEs 206 to increase the overall system capacity. This isachieved by spatially precoding each data stream (i.e., applying ascaling of an amplitude and a phase) and then transmitting eachspatially precoded stream through multiple transmit antennas on the DL.The spatially precoded data streams arrive at the UE(s) 206 withdifferent spatial signatures, which enables each of the UE(s) 206 torecover the one or more data streams destined for that UE 206. On theUL, each UE 206 transmits a spatially precoded data stream, whichenables the eNB 204 to identify the source of each spatially precodeddata stream.

Spatial multiplexing is generally used when channel conditions are good.When channel conditions are less favorable, beamforming may be used tofocus the transmission energy in one or more directions. This may beachieved by spatially precoding the data for transmission throughmultiple antennas. To achieve good coverage at the edges of the cell, asingle stream beamforming transmission may be used in combination withtransmit diversity.

In the detailed description that follows, various aspects of an accessnetwork will be described with reference to a MIMO system supportingOFDM on the DL. OFDM is a spread-spectrum technique that modulates dataover a number of subcarriers within an OFDM symbol. The subcarriers arespaced apart at precise frequencies. The spacing provides“orthogonality” that enables a receiver to recover the data from thesubcarriers. In the time domain, a guard interval (e.g., cyclic prefix)may be added to each OFDM symbol to combat inter-OFDM-symbolinterference. The UL may use SC-FDMA in the form of a DFT-spread OFDMsignal to compensate for high peak-to-average power ratio (PAPR).

FIG. 3 is a diagram 300 illustrating an example of a DL frame structurein LTE. A frame (10 ms) may be divided into 10 equally sized subframes.Each subframe may include two consecutive time slots. A resource gridmay be used to represent two time slots, each time slot including aresource block. The resource grid is divided into multiple resourceelements. In LTE, for a normal cyclic prefix, a resource block contains12 consecutive subcarriers in the frequency domain and 7 consecutiveOFDM symbols in the time domain, for a total of 84 resource elements.For an extended cyclic prefix, a resource block contains 12 consecutivesubcarriers in the frequency domain and 6 consecutive OFDM symbols inthe time domain, for a total of 72 resource elements. Some of theresource elements, indicated as R 302, 304, include DL reference signals(DL-RS). The DL-RS include Cell-specific RS (CRS) (also sometimes calledcommon RS) 302 and UE-specific RS (UE-RS) 304. UE-RS 304 are transmittedon the resource blocks upon which the corresponding physical DL sharedchannel (PDSCH) is mapped. The number of bits carried by each resourceelement depends on the modulation scheme. Thus, the more resource blocksthat a UE receives and the higher the modulation scheme, the higher thedata rate for the UE.

FIG. 4 is a diagram 400 illustrating an example of an UL frame structurein LTE. The available resource blocks for the UL may be partitioned intoa data section and a control section. The control section may be formedat the two edges of the system bandwidth and may have a configurablesize. The resource blocks in the control section may be assigned to UEsfor transmission of control information. The data section may includeall resource blocks not included in the control section. The UL framestructure results in the data section including contiguous subcarriers,which may allow a single UE to be assigned all of the contiguoussubcarriers in the data section.

A UE may be assigned resource blocks 410 a, 410 b in the control sectionto transmit control information to an eNB. The UE may also be assignedresource blocks 420 a, 420 b in the data section to transmit data to theeNB. The UE may transmit control information in a physical UL controlchannel (PUCCH) on the assigned resource blocks in the control section.The UE may transmit data or both data and control information in aphysical UL shared channel (PUSCH) on the assigned resource blocks inthe data section. A UL transmission may span both slots of a subframeand may hop across frequency.

A set of resource blocks may be used to perform initial system accessand achieve

UL synchronization in a physical random access channel (PRACH) 430. ThePRACH 430 carries a random sequence and cannot carry any ULdata/signaling. Each random access preamble occupies a bandwidthcorresponding to six consecutive resource blocks. The starting frequencyis specified by the network. That is, the transmission of the randomaccess preamble is restricted to certain time and frequency resources.There is no frequency hopping for the PRACH. The PRACH attempt iscarried in a single subframe (1 ms) or in a sequence of few contiguoussubframes and a UE can make a single PRACH attempt per frame (10 ms).

FIG. 5 is a diagram 500 illustrating an example of a radio protocolarchitecture for the user and control planes in LTE. The radio protocolarchitecture for the UE and the eNB is shown with three layers: Layer 1,Layer 2, and Layer 3. Layer 1 (L1 layer) is the lowest layer andimplements various physical layer signal processing functions. The L1layer will be referred to herein as the physical layer 506. Layer 2 (L2layer) 508 is above the physical layer 506 and is responsible for thelink between the UE and eNB over the physical layer 506.

In the user plane, the L2 layer 508 includes a media access control(MAC) sublayer 510, a radio link control (RLC) sublayer 512, and apacket data convergence protocol (PDCP) 514 sublayer, which areterminated at the eNB on the network side. Although not shown, the UEmay have several upper layers above the L2 layer 508 including a networklayer (e.g., IP layer) that is terminated at the PDN gateway 118 on thenetwork side, and an application layer that is terminated at the otherend of the connection (e.g., far end UE, server, etc.).

The PDCP sublayer 514 provides multiplexing between different radiobearers and logical channels. The PDCP sublayer 514 also provides headercompression for upper layer data packets to reduce radio transmissionoverhead, security by ciphering the data packets, and handover supportfor UEs between eNBs. The RLC sublayer 512 provides segmentation andreassembly of upper layer data packets, retransmission of lost datapackets, and reordering of data packets to compensate for out-of-orderreception due to hybrid automatic repeat request (HARQ). The MACsublayer 510 provides multiplexing between logical and transportchannels. The MAC sublayer 510 is also responsible for allocating thevarious radio resources (e.g., resource blocks) in one cell among theUEs. The MAC sublayer 510 is also responsible for HARQ operations.

In the control plane, the radio protocol architecture for the UE and eNBis substantially the same for the physical layer 506 and the L2 layer508 with the exception that there is no header compression function forthe control plane. The control plane also includes a radio resourcecontrol (RRC) sublayer 516 in Layer 3 (L3 layer). The RRC sublayer 516is responsible for obtaining radio resources (e.g., radio bearers) andfor configuring the lower layers using RRC signaling between the eNB andthe UE.

FIG. 6 is a block diagram of an eNB 610 in communication with a UE 650in an access network. In the DL, upper layer packets from the corenetwork are provided to a controller/processor 675. Thecontroller/processor 675 implements the functionality of the L2 layer.In the DL, the controller/processor 675 provides header compression,ciphering, packet segmentation and reordering, multiplexing betweenlogical and transport channels, and radio resource allocations to the UE650 based on various priority metrics. The controller/processor 675 isalso responsible for HARQ operations, retransmission of lost packets,and signaling to the UE 650.

The transmit (TX) processor 616 implements various signal processingfunctions for the L1 layer (i.e., physical layer). The signal processingfunctions include coding and interleaving to facilitate forward errorcorrection (FEC) at the UE 650 and mapping to signal constellationsbased on various modulation schemes (e.g., binary phase-shift keying(BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying(M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded andmodulated symbols are then split into parallel streams. Each stream isthen mapped to an OFDM subcarrier, multiplexed with a reference signal(e.g., pilot) in the time and/or frequency domain, and then combinedtogether using an Inverse Fast Fourier Transform (IFFT) to produce aphysical channel carrying a time domain OFDM symbol stream. The OFDMstream is spatially precoded to produce multiple spatial streams.Channel estimates from a channel estimator 674 may be used to determinethe coding and modulation scheme, as well as for spatial processing. Thechannel estimate may be derived from a reference signal and/or channelcondition feedback transmitted by the UE 650. Each spatial stream maythen be provided to a different antenna 620 via a separate transmitter618TX. Each transmitter 618TX may modulate an RF carrier with arespective spatial stream for transmission.

At the UE 650, each receiver 654RX receives a signal through itsrespective antenna 652. Each receiver 654RX recovers informationmodulated onto an RF carrier and provides the information to the receive(RX) processor 656. The RX processor 656 implements various signalprocessing functions of the L1 layer. The RX processor 656 may performspatial processing on the information to recover any spatial streamsdestined for the UE 650. If multiple spatial streams are destined forthe UE 650, they may be combined by the RX processor 656 into a singleOFDM symbol stream. The RX processor 656 then converts the OFDM symbolstream from the time-domain to the frequency domain using a Fast FourierTransform (FFT). The frequency domain signal comprises a separate OFDMsymbol stream for each subcarrier of the OFDM signal. The symbols oneach subcarrier, and the reference signal, are recovered and demodulatedby determining the most likely signal constellation points transmittedby the eNB 610. These soft decisions may be based on channel estimatescomputed by the channel estimator 658. The soft decisions are thendecoded and deinterleaved to recover the data and control signals thatwere originally transmitted by the eNB 610 on the physical channel. Thedata and control signals are then provided to the controller/processor659.

The controller/processor 659 implements the L2 layer. Thecontroller/processor 659 can be associated with a memory 660 that storesprogram codes and data. The memory 660 may be referred to as acomputer-readable medium. In the UL, the controller/processor 659provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover upper layer packets from the core network. The upper layerpackets are then provided to a data sink 662, which represents all theprotocol layers above the L2 layer. Various control signals may also beprovided to the data sink 662 for L3 processing. Thecontroller/processor 659 is also responsible for error detection usingan acknowledgement (ACK) and/or negative acknowledgement (NACK) protocolto support HARQ operations.

In the UL, a data source 667 is used to provide upper layer packets tothe controller/processor 659. The data source 667 represents allprotocol layers above the L2 layer. Similar to the functionalitydescribed in connection with the DL transmission by the eNB 610, thecontroller/processor 659 implements the L2 layer for the user plane andthe control plane by providing header compression, ciphering, packetsegmentation and reordering, and multiplexing between logical andtransport channels based on radio resource allocations by the eNB 610.The controller/processor 659 is also responsible for HARQ operations,retransmission of lost packets, and signaling to the eNB 610.

Channel estimates derived by a channel estimator 658 from a referencesignal or feedback transmitted by the eNB 610 may be used by the TXprocessor 668 to select the appropriate coding and modulation schemes,and to facilitate spatial processing. The spatial streams generated bythe TX processor 668 may be provided to different antenna 652 viaseparate transmitters 654TX. Each transmitter 654TX may modulate an RFcarrier with a respective spatial stream for transmission.

The UL transmission is processed at the eNB 610 in a manner similar tothat described in connection with the receiver function at the UE 650.Each receiver 618RX receives a signal through its respective antenna620. Each receiver 618RX recovers information modulated onto an RFcarrier and provides the information to a RX processor 670. The RXprocessor 670 may implement the L1 layer.

The controller/processor 675 implements the L2 layer. Thecontroller/processor 675 can be associated with a memory 676 that storesprogram codes and data. The memory 676 may be referred to as acomputer-readable medium. In the UL, the controller/processor 675provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover upper layer packets from the UE 650. Upper layer packets fromthe controller/processor 675 may be provided to the core network. Thecontroller/processor 675 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

For Internet-of-everything (IoE) uplink, the number of UEs may be morethan the number available time/frequency resources. A time/frequencyresource may be the resource in a symbol period on a particular tone (orfrequency).

A UE may use resource shared multiple access (RSMA) to sharetime/frequency resources. In other words, multiple UEs can use the sametime/frequency resources to transmit uplink signals to a base station.The base station may perform successive-decoding. In particular, thebase station may decode signals from one UE while treating signals fromother UEs as noise. The decoded signals may be canceled or subtractedfrom the received combined signals after decoding.

FIG. 7 is a diagram 700 illustrating communication between an eNodeB andtwo UEs utilizing RSMA. In a first technique, a UE 752 maps, in aparticular symbol period, one or more pilot symbols 762, each on a tone770, and maps one or more data symbols 766, each on a tone 770. Further,a UE 753 maps, in the same symbol period, one or more pilot symbols 763,each on a tone 770, and maps one or more data symbols 767, each on atone 770. As an example, FIG. 7 illustrates 2 pilot symbols 762 and 6data symbols 766 at the UE 752 and 2 pilot symbols 763 and 6 datasymbols 767 at the UE 753. A pilot symbol 762 is mapped on the same tone770 of a pilot symbol 763. A data symbol 766 is mapped on the same tone770 of a data symbol 767. Further, the pilot symbols 762 and the datasymbols 766 are sent to an IFFT component 774 of the UE 752, at which aninverse fast Fourier transform is applied to the pilot symbols 762. TheIFFT component 774 sends the generated signals to a parallel-to-serialconverter 776, which performs a parallel-to-serial conversion to thegenerated signals. The output from the parallel-to-serial converter 776is a time domain signal, which is transmitted to the eNodeB 702 throughan antenna 782. Similarly, the pilot symbols 763 and the data symbols767 are sent to an IFFT component 775 of the UE 753. The IFFT component775 sends the generated signals to a parallel-to-serial converter 777,which generates a time domain signal that is transmitted to the eNodeB702 through an antenna 783.

The eNodeB 702 receives the combined time domain signals transmittedfrom the UE 752 and the UE 753 at an antenna 712. The received combinedsignals are sent to a serial-to-parallel converter 714 forserial-to-parallel conversion. The serial-to-parallel converter 714sends the converted combined signal to an FFT component 716, at which aFast Fourier Transform is applied to the converted combined signal togenerate a combined signal on each of the tones 770. Each combinedsignal may include a signal derived from a symbol transmitted from theUE 752 and a signal derived from a symbol transmitted from the UE 753.For example, the UE 752 transmits a pilot symbol 762 on a first tone770-1 to the eNodeB 702, and the UE 753 transmits a pilot symbol 763 onthe first tone 770-1 to the eNodeB 702. Accordingly, the FFT component716 outputs on the first tone 770-1 a combined signal that includes apilot signal derived from the pilot symbol 762 and a pilot signalderived from the pilot symbol 763. Further, the UE 752 transmits a datasymbol 766 on a second tone 770-2 to the eNodeB 702, and the UE 753transmits a data symbol 767 on the second tone 770-2 to the eNodeB 702.Accordingly, the FFT component 716 outputs on the second tone 770-2 acombined signal that includes a data signal derived from the data symbol766 and a data signal derived from the data symbol 767.

As described above, upon obtaining the combined signal on a tone 770,the eNodeB 702 may attempt demodulate and decode the pilot signal or thedata signal derived from the symbol of one of the UEs 752, 753 whiletreating the corresponding pilot signal or the corresponding data signalderived from the symbol of the other one of the UEs 752, 753 as noise.It has been observed that the demodulation and decoding accuracy of thistechnique may not be ideal and may be further improved.

In a second technique, different UEs may be configured to map theirrespective pilot symbols (e.g., modulated symbols) on differenttime/frequency resources. As described below, staggered pilot placementmay provide non-overlapping pilot placement. In the staggered pilotplacement, each UE may shift its periodic pilot placement with adifferent cyclic shift in frequency. This non-overlapping pilotplacement may be exploited in a pilot-aid interference cancellation(PIC) decoder.

FIG. 8 is a diagram 800 illustrating communication between an eNodeB andtwo UEs. Referring to FIG. 8, a UE 852 maps one or more pilot symbols862 and one or more data symbols 866 on tones 870. The pilot symbols anddata symbols may be modulated symbols (e.g., modulated by QPSK, QAM,etc.). Further, each of the pilot symbols 862 is on a tone that carriesone of the data symbols 867. A UE 853 maps one or more pilot symbols 863and one or more data symbols 867 on the tones 870. In this disclosure,p_(i,j) denotes a j^(th) pilot symbol at the i^(th) UE. x_(i,j) denotesa j^(th) data symbol at the i^(th) UE. More specifically, FIG. 8 showsthat, as an example, the UE 852 maps p_(1,1), x_(1,1), x_(1,2), x_(1,3),p_(1,2), x_(1,4), x_(1,5), x_(1,6) in that order on 8 tones 870. The UE853 maps x_(2,1), p_(2,1), x_(2,2), x_(2,3), x_(2,4), p_(2,2), x_(2,5),x_(2,6) in that order on the same 8 tones 870. As shown in FIG. 8, thepilot locations for the UE 853 may be cyclically shifted from the pilotlocations for the UE 852. In one aspect, the cyclic shift amount may besignaled and assigned by the eNodeB 802. The signaling may be unicastedto individual UEs or broadcasted with a UE identifier, such that each UEmay determine a cyclic shift value based on its respective UEidentifier. In another aspect, the UE 852, for example, may randomlyselect from among a set of cyclic shift values based on the identifierfor the UE 852. That is, the cyclic shift value may be a function of theUE identifier.

The pilot symbols 862 and the data symbols 866 are processed by an IFFTcomponent 874 and a parallel-to-serial converter 876 of the UE 852 togenerate a time domain signal. The pilot symbols 863 and the datasymbols 867 are processed by an IFFT component 875 and aparallel-to-serial converter 877 of the UE 853 to generate a time domainsignal.

An eNodeB 802 receives the combined signals transmitted from the UE 852and the UE 853, and the received combined signals are processed by aserial-to-parallel converter 814 and an FFT component 816 to generatethe combined signal on each of the tones 870.

Further, s_(1,k) denotes the symbol (i.e., a pilot symbol 862 or a datasymbol 866) transmitted by the UE 852 on the k^(th) tone. s_(2,k)denotes the symbol (i.e., a pilot symbol 863 or a data symbol 867)transmitted by the UE 853 on the k^(th) tone. y_(k) denotes the combinedsignal generated by the FFT component 816 on the k^(th) tone. A channelmatrix for the k^(th) tone is:

$H_{k} = \begin{pmatrix}h_{1,k} & 0 \\0 & h_{2,k}\end{pmatrix}$

The combined signal y_(k) is:

$y_{k} = {\begin{pmatrix}h_{1,k} & 0 \\0 & h_{2,k}\end{pmatrix}\begin{pmatrix}s_{1,k} \\s_{2,k}\end{pmatrix}}$

where the noise on the k^(th) tone has been eliminated or ignored. Forexample, on the first tone 870-1 and the second tone 870-2, the combinedsignals are:

y ₁ =h _(1,1) p _(1,1) +h _(2,1) x _(2,1)

y ₂ =h _(1,2) x _(1,1) +h _(2,2) p _(2,1)

Subsequently, the FFT component 816 sends the combined signals to a PICdecoder 822.

FIG. 9 is a diagram 900 illustrating demodulation and decodingprocedures at an eNodeB. The PIC decoder 822 of the eNodeB 802 receivesthe combined signal on each tone 870. For a k^(th) tone carrying a pilotsymbol from either the UE 852 or the UE 853, the PIC decoder 822 knowsthe estimated channel h′_(i,k) and p_(i,k), where i is 1 or 2 in thisexample. In an aspect, the PIC decoder 822 may know the estimatedchannel h′_(i,k) based on UE feedback and/or prior transmissions, andp_(i,k) may be preconfigured. Thus, the PIC decoder 822 can estimate apilot signal derived from the p_(i,k): h′_(i,k)p_(i,k). The PIC decoder822 may cancel the pilot signal h′_(i,k)p_(i,k) from the combined signaly_(k) (e.g., i may be 1 and may indicate a pilot symbol from the UE852). The remaining signal of the combined signal is a data signalderived from the data symbol from the other UE on the k^(th) tone. Assuch, the PIC decoder 822 may cancel the pilot signals on the tones 870.In this way, the noise or interference are reduced for the remainingdata signals.

FIG. 9 shows that in this example, the 1^(st), 2^(nd), 5^(th) and 6^(th)tones 870 each carry a pilot signal. Accordingly, the remaining signalson those tones are:

y ₁ −h′ _(1,1) p _(1,1) =h _(1,1) p _(1,1) +h _(2,1) x _(2,1) −h′ _(1,1)p _(1,1)

y ₂ −h′ _(2,2) p _(2,1) =h _(1,2) x _(1,1) +h _(2,2) p _(2,1) −h′ _(2,2)p _(2,1)

y ₅ −h′ _(1,5) p _(1,2) =h _(1,5) p _(1,2) +h _(2,5) x _(2,4) −h′ _(1,5)p _(1,2)

y ₆ −h′ _(2,6) p _(2,2) =h _(1,6) x _(1,4) +h _(2,6) p _(2,2) −h′ _(2,6)p _(2,2)

Subsequently, the PIC decoder 822 sends the remaining signals (e.g.,data signals) to a multi-user decoder 826. The multi-user decoder 826may decode the remaining signals to obtain the information from the datasymbols from the UE 852 and the UE 853 carried on the tones 870. Forexample, the multi-user decoder 826 may be a successive interferencedecoder.

One transmission block (spans over one or multiple OFDM symbol periods)may include pilot tones and multiple code blocks. In an aspect, codeblocks may include data symbols or bits but not pilot symbols. Inadditional to staggered pilot placement, in a third technique, each codeblock may be allocated as described below to facilitate the successivedecoding. In certain configurations, one UE may allocate code blocks ina way such that data symbols on the tones that also carry pilot symbolsfrom another UE belong to the same code block.

FIG. 10 is a diagram 1000 illustrating procedures of mapping pilotsymbols and data symbols at a UE. A UE 1052 has information that the2^(nd) and the 6^(th) tones 1070 carry pilot symbols (e.g., p_(2,1) andp_(2,2)) from a UE 1053. Thus, an interleaver 1090 of the UE 1052 mayallocate data symbols derived from information bits of the same codeblock (e.g., a code block 1092) to the 2^(nd) and the 6^(th) tones.Similarly, the UE 1053 has information that the 1^(st) and the 5^(th)tones 1070 carry pilot symbols (e.g., p_(1,1) and p_(1,2)) from the UE1052. Thus, an interleaver 1091 of the UE 1053 may allocate data symbolsderived from information bits of the same code block (e.g., a code block1093) to the 1^(st) and the 5^(th) tones.

FIG. 11 is a diagram 1100 illustrating demodulation and decodingprocedures at an eNodeB. An eNodeB 1002 receives pilot signals 1032 anddata signals 1036 on the tones 1070 from the UE 1052. The eNodeB 1002also receives pilot signals 1033 and data signals 1037 on the tones 1070from the UE 1053. As shown in FIG. 11, the pilot signals 1033 have beensubjected to a different cyclic shift than the pilot signals 1032. In anaspect, a cyclic shift may be different from a frequency offset. When acyclic shift is performed, all of the tones may still be occupied, butthe pilot tone locations may be shifted. By contrast, when a frequencyoffset is performed, certain tones from which the offset begins may beleft empty.

Referring to FIG. 11, the eNodeB 1002 has information that, as describedsupra, the tones 1070 carrying the pilot signals 1032 also carry datasignals 1037 derived from the information bits of the same code block,e.g., the code block 1093. Further, the tones 1070 carrying the pilotsignals 1033 also carry data signals 1036 derived from the informationbits of the same code block, e.g., the code block 1092.

Using the second technique described supra, the eNodeB 1002 may estimatethe pilot signals 1032 and may cancel the pilot signals 1032 from thecombined signals carried on those tones 1070 carrying the pilot signals1032. The remaining signals on the tones 1070 carrying the pilot signals1032 are data signals 1037 derived from the code block 1093 of the UE1053. After a deinterleaving procedure 1040, the pilot signals 1032 fromthe UE 1052 overlap with the data signals 1037 derived from the codeblock 1093 of the UE 1053. That is, all the pilot signals 1032 from theUE 1052 may overlap with the code block 1093 of the UE 1053. As anexample, the number of tones carrying the pilot signals 1032 may be halfof the number of tones carrying the data signals 1037 derived from thecode block 1093. As such, the eNodeB 1002 may be able to demodulate anddecode all the data signals 1037 derived from the code block 1093 moreaccurately. The eNodeB 1002 may thus obtain codewords of the code block1093.

Further, as illustrated in FIG. 11, after the deinterleaving procedure1040, the tones 1070 carrying the data signals 1037 derived from thecode block 1093 overlap with the tones 1070 carrying the data signals1036 derived from the code block 1094. As such, the eNodeB 1002 maycancel the data signals 1037 derived the code block 1093 from thecombined signals carried on the overlapping tones. The remaining signalson the overlapping tones are data signals 1036 derived from the codeblock 1094. In this way, the eNodeB 1002 may be able to demodulate anddecode all the data signals 1036 derived from the code block 1094 moreaccurately. The eNodeB 1002 may thus obtain codewords of the code block1094.

Similarly to what was described supra, the tones 1070 carrying the datasignals 1036 derived from the code block 1094 overlap with the tones1070 carrying the data signals 1037 derived from the code block 1095.The eNodeB 1002 may cancel the data signals 1036 derived from the codeblock 1094 in order to demodulate and decode the data signals 1037derived from the code block 1095.

Further, the tones 1070 carrying the data signals 1037 derived from thecode block 1095 overlap with the tones 1070 carrying the data signals1036 derived from the code block 1092. The tones 1070 carrying the pilotsignals 1033 may also overlap with the tones 1070 carrying the datasignals 1036 derived from the code block 1092. As such, the eNodeB 1002may cancel the data signals 1037 derived from the code block 1095 and/orthe pilot signals 1033 in order to demodulate and decode the datasignals 1036 derived from the code block 1092.

In other words, the efficiency of the PIC decoder 822 may be furtherimproved by carefully designing interleavers. The PIC decoder 822 mayassume that pilot tones are not aligned, but data bits may beselectively located to improve performance. For example, for the UE1052, the data bits from CB11 are located in the tones that correspondto the pilot locations of UE 1053. For UE 1053, the data bits from CB21may be located in the tones that correspond to the pilot locations of UE1052. That is, all of the pilot locations from UE 1052 correspond toCB21 of the UE 1053. Referring to FIG. 11, after deinterleaving, all thepilot locations of the UE 1052 may overlap with the data bits from CB21of the UE 1053, and all the pilot locations of the UE 1052 may overlapwith the data bits from CB11 of the UE 1052. Based on the foregoingcyclic shifts in frequency and alignments, successive decoding may beperformed. For example, the pilot signals 1032 are canceled from CB21and CB21 may be decoded. CB21 may be canceled from CB12, and then CB12may be decoded. Then, CB12 may be canceled from CB22, and CB22 may bedecoded. Then, CB22 may be canceled from CB11, and CB11 may be decoded.In an aspect, the pilot signals 1033 may be canceled from CB11 beforeCB11 is decoded. As shown in FIG. 11, each code block of the UE 1053 mayoverlap with at most two code blocks of the UE 1052, and vice versa. Ifthe code block from the UE 1052 overlaps with the pilot signals from theUE 1053, the then the code block only overlaps with one other code blockof the UE 1053, and vice versa. Although FIG. 11 illustrates thesuccessive decoding process starting from the pilot signals 1032, thedecoding process may also begin from the bottom at the pilot signals1033. If the decoding process fails in both directions, then the eNodeB1002 may determine that the decoding has failed. Otherwise, if thedecoding only fails in one direction, the eNodeB 1002 may attemptdecoding in a different direction. In another aspect, because the CB11has a greater amount of interference canceled (e.g., interference fromCB22 and from the pilot signals 1033), the UE 1052 may transmit CB22 ata higher MCS compared with other code blocks (e.g., CB12). The same maybe true of the UE 1053 for CB21. In other words, UEs may transmit codeblocks that overlap with another UE's pilot tone locations at a higherMCS than code blocks that do no overlap with another UE's pilot tonelocations.

FIG. 12 is a flow chart 1200 of a method (process) for interferencereduction, de-interleaving, and demodulation. The method may beperformed by a base station (e.g., the eNodeB 802, the eNodeB 1002).

At 1202, the base station may receive a plurality of combined signals.Each combined signal may be on a tone of a plurality of tones. Eachcombined signal may include a first symbol of a first plurality ofsymbols (e.g., modulated symbols) from a first UE and a second symbol ofa second plurality of symbols from a second UE. The first plurality ofsymbols may include at least one first pilot symbol and at least onefirst data symbol, and the second plurality of symbols may includeincluding at least one second pilot symbol and at least one second datasymbol. Each of the at least one first pilot symbol may be on a tonethat carries one of the at least one second data symbol, and each ofthat least one second pilot symbol may be on a tone that carries one ofthe at least one first data symbol. For example, referring to FIG.8, thebase station may be the eNodeB 802. The eNodeB 802 may receive thecombined signals. Each combined signal (e.g., y₁) may include a firstsymbol of a first plurality of symbols from the UE 852 (the first UE)and a second symbol of a second plurality of symbols from the UE 853(the second UE). The first plurality of symbols may include the firstpilot symbol p_(1,1) and the first data symbol x_(1,1). The secondplurality of symbols from the UE 853 may include the second pilot symbolp_(2,1) and the second data symbol x_(2,1). The first pilot symbol maybe on a tone that carries the second data symbol x_(2,1), and the secondpilot symbol p_(2,1) may be on a different tone that carries the firstdata symbol x_(1,1).

At 1204, the base station may determine a first pilot signal on a firsttone of the plurality of tones. The first tone may carry a respectiveone of the at least one first pilot symbol and a respective one of theat least one second data symbol. The first pilot signal may bedetermined based on a channel element associated with the first tone andthe respective one of the at least one first pilot symbol on the firsttone. For example, referring to FIGS. 8 and 9, the eNodeB 802 maydetermine the first pilot signal, h′_(1,1)p_(1,1), on a first tone ofthe tones 870. The first tone may carry the first pilot symbol, p_(1,1),from the UE 852 and the second data symbol, x_(2,1), from the UE 853.The pilot signal, h′_(1,1)p_(1,1), may be determined based on thechannel element, h′_(1,1), associated with the first tone and therespective first pilot symbol p_(1,1). In an aspect, the channel elementmay be determined based on received feedback from the UE 852 thatindicates the channel element.

At 1206, the base station may generate an interference-reduced signalfor the first tone by canceling the determined first pilot signal from afirst combined signal on the first tone. For example, referring to FIGS.8 and 9, the eNodeB 802 may generate the interference-reduced signal forthe first tone, y₁−h′_(1,1)p_(1,1), by canceling the determined firstpilot signal, h′_(1,1)p_(1,1), from the first combined signal, y₁, onthe first tone.

At 1208, the base station may determine a second pilot signal on asecond tone of the plurality of tones. The second tone may carry arespective one of the at least one second pilot symbol and a respectiveone of the at least one first data symbol. The second pilot signal maybe determined based on a second channel element associated with thesecond tone and the respective one of the at least one second pilotsymbol on the second tone. For example, referring to FIGS. 8 and 9, theeNodeB 802 may determine the second pilot signal, h′_(2,2)p_(2,1), on asecond tone of the tones 870. The second tone may carry the second pilotsymbol, p_(2,1), from the UE 853 and the first data symbol, x_(1,1),from the UE 852. The second pilot signal, h′_(2,2)p_(2,1), may bedetermined based on the channel element, h′_(2,2), associated with thesecond tone and the respective second pilot symbol p_(2,1).

At 1210, the base station may generate a second interference-reducedsignal for the second tone by canceling the determined second pilotsignal from a second combined signal on the second tone. For example,referring to FIGS. 8 and 9, the eNodeB 802 may generated the secondinterference-reduced signal for the second tone, y₂−h′_(2,2)p_(2,1), bycanceling the determined first pilot signal, h′_(2,2)p_(2,1), from thesecond combined signal, y₂, on the second tone.

At 1212, the base station may de-interleave the plurality of combinedsignals to determine a first set of pilot signals from the first UE,first and second code blocks from the first UE, a second set of pilotsignals from the second UE, and third and fourth code blocks from thesecond UE. For example, referring to FIGS. 8 and 11, the eNodeB 802 (orthe eNodeB 1002) may de-interleave the plurality of combined signals(e.g., y₁, y₂) to determine the pilot signals 1032 (the first set ofpilot signals) from the UE 852, the first and second code blocks (CB11and CB12) from the UE 852, the pilot signals 1033 (the second set ofpilot signals) from the UE 853, and the third and fourth code blocks(CB21 and CB22) from the UE 853. In an aspect, the eNodeB 802 mayde-interleave by arranging and demodulating the first set of pilotsignals in a first portion of the tones, arranging and demodulating thefirst code block in a second portion of the tones, and arranging anddemodulating the second code block in a third set of the tones.

At 1214, the base station may perform successive decoding afterde-interleaving the plurality of combined signals. In one configuration,the base station may perform successive decoding by decoding the thirdcode block by canceling the first set of pilot signals from the thirdcode block, by decoding the first code block by canceling the third codeblock from the first code block, by decoding the fourth code block bycanceling the first code block from the fourth code block, and bydecoding the second code block by canceling the fourth code block fromthe second code block. For example, referring to FIGS. 8 and 11, theeNodeB 802 may perform success decoding by decoding CB21 by cancelingthe pilot signals 1032 from the CB21, by decoding CB12 by canceling thecorresponding tones in CB21 from CB12, by decoding CB22 by canceling thecorresponding tones from CB12 from CB22, and by decoding CB11 bycanceling the corresponding tones from CB22 from CB11. In an aspect,CB11 may have corresponding tones canceled from CB22 and from the pilotsignals 1033. As such, compared to other code blocks, CB11 may haveimproved accuracy. In this aspect, CB11 may be transmitted with a higherMCS index than other codeblocks.

In an aspect, as shown in FIG. 8, the pilot signals 1032 from the UE1052 are shifted by a cyclic shift as compared to the pilot signals 1033from the UE 1053. The cyclic shift may be provided (or transmitted) bythe eNodeB 1002 to each of the UEs 1052, 1053.

FIG. 13 is a flow chart 1300 of a method (process) for mapping pilotsymbols and data symbols on multiple tones. The method may be performedby a UE (e.g., the UEs 852, 853, 1052, 1053).

At 1302, the UE may receive a cyclic shift for staggering pilot symbolsfrom a base station. For example, referring to FIG. 8, the UE may be theUE 852. The UE 852 may receive a cyclic shift for staggering pilotsymbols 862 from the eNodeB 802. Alternatively, the UE 852 may notreceive the cyclic shift from the eNodeB 802. Instead, the UE 852 mayselect the cyclic shift from among a set of cyclic shifts based on anidentifier associated with the UE 852.

At 1304, the UE may map a first set of pilot symbols and a first set ofdata symbols to a plurality of tones. Each pilot symbol in the first setof pilot symbols being mapped on a tone that is used by a second UE tocarry a data symbol. For example, referring to FIG. 8, the UE 852 maymap the pilot symbols p_(1,1) and p_(1,2) and a first set of datasymbols x_(1,1), x_(1,2), x_(1,3), x_(1,4), x_(1,5), x_(1,6). The UE 852may map the pilot symbols p_(1,1) and p_(1,2) onto tones used by the UE853 (the second UE) to carry a data symbol, such as the data symbolx_(2,1). In an aspect, the UE 852 may select the tone locations to mapthe pilot symbols based on a cyclic shift. The UE 852 may receive thecyclic shift from the eNodeB 802 or determine the cyclic shift. The UE852 may determine which tones are used by other UEs, such as the UE 853,to transmit pilot symbols and map data symbols onto those tones.

At 1306, the UE may provide the first set of pilot symbols and the firstset of data symbols for transmission over the plurality of tones. Forexample, referring to FIG. 8, the UE 852 may provide the pilot symbolsp_(1,1) and p_(1,2) and a first set of data symbols x_(1,1), x_(1,2),x_(1,3), x_(1,4), x_(1,5), x_(1,6) for transmission over the tones byindicating the tones on which the modulated symbols are to betransmitted and placing the tone indication along with the modulatedsymbols on a bus to be transmitted via a transmitter or a transceiver.

FIG. 14 is a conceptual data flow diagram 1400 illustrating the dataflow between different means/components in an exemplary apparatus 1402.The apparatus may be an eNB. The apparatus includes a receptioncomponent 1404, a deinterleaver component 1406, a decoding component1408, and a transmission component 1410. The reception component 1404may be configured to receive a plurality of combined signals. Eachcombined signal may be on a tone of a plurality of tones. Each combinedsignal may include a first symbol of a first plurality of symbols from afirst UE and a second symbol of a second plurality of symbols from asecond UE. The first plurality of symbols may include at least one firstpilot symbol and at least one first data symbol. The second plurality ofsymbols may include at least one second pilot symbol and at least onesecond data symbol. Each of the at least one first pilot symbol may beon a tone that carries one of the at least one second data symbol. Thedeinterleaver component 1406 may be configured to determine a firstpilot signal on a first tone of the plurality of tones. The first tonemay carry a respective one of the at least one first pilot symbol and arespective one of the at least one second data symbol. The first pilotsignal may be determined based on a channel element associated with thefirst tone and the respective one of the at least one first pilot symbolon the first tone. The decoding component 1408 may be configured togenerate an interference-reduced signal for the first tone by cancelingthe determined first pilot signal from a first combined signal on thefirst tone. In another configuration, the deinterleaver component 1406may be configured to determine a second pilot signal on a second tone ofthe plurality of tones. The second tone may carry a respective one ofthe at least one second pilot symbol and a respective one of the atleast one first data symbol. The second pilot signal may be determinedbased on a second channel element associated with the second tone andthe respective one of the at least one second pilot symbol on the secondtone. The decoding component 1408 may be configured to generate a secondinterference-reduced signal for the second tone by canceling thedetermined second pilot signal from a second combined signal on thesecond tone. In an aspect, a first set of periodic pilot signals fromthe first UE and a second set of periodic pilot signals from the secondUE are shifted by a cyclic shift. In another aspect, the transmissioncomponent 1410 may be configured to provide a cyclic shift to the firstUE. In another configuration, the deinterleaver component 1406 may beconfigured to deinterleave the plurality of combined signals todetermine a first set of pilot signals from the first UE, first andsecond code blocks from the first UE, a second set of pilot signals fromthe second UE, and third and fourth code blocks from the second UE. Inan aspect, the first set of pilot signals may correspond to a firstnumber tones. The first number tones may be equal to half a secondnumber of tones in the third code block. In another aspect, the firstset of pilot signals from the first UE may overlap with the third codeblock from the second UE, and the second set of pilot signals from thesecond UE may overlap with the second code block from the first UE. Inanother configuration, the decoding component 1408 may be configured toperform successive decoding after deinterleaving the plurality ofcombined signals. In another configuration, the decoding component 1408may be configured to perform successive decoding by decoding the thirdcode block by canceling the first set of pilot signals from the thirdcode block, by decoding the first code block by canceling the third codeblock from the first code block, by decoding the fourth code block bycanceling the first code block from the fourth code block, and bydecoding the second code block by canceling the fourth code block fromthe second code block.

The apparatus may include additional components that perform each of theblocks of the algorithm in the aforementioned flowcharts of FIG. 13. Assuch, each block in the aforementioned flowcharts of FIG. 13 may beperformed by a component and the apparatus may include one or more ofthose components. The components may be one or more hardware componentsspecifically configured to carry out the stated processes/algorithm,implemented by a processor configured to perform the statedprocesses/algorithm, stored within a computer-readable medium forimplementation by a processor, or some combination thereof.

FIG. 15 is a diagram 1500 illustrating an example of a hardwareimplementation for an apparatus 1402′ employing a processing system1514. The processing system 1514 may be implemented with a busarchitecture, represented generally by the bus 1524. The bus 1524 mayinclude any number of interconnecting buses and bridges depending on thespecific application of the processing system 1514 and the overalldesign constraints. The bus 1524 links together various circuitsincluding one or more processors and/or hardware components, representedby the processor 1504, the components 1404, 1406, 1408, 1410, and thecomputer-readable medium/memory 1506. The bus 1524 may also link variousother circuits such as timing sources, peripherals, voltage regulators,and power management circuits, which are well known in the art, andtherefore, will not be described any further.

The processing system 1514 may be coupled to a transceiver 1510. Thetransceiver 1510 is coupled to one or more antennas 1520. Thetransceiver 1510 provides a means for communicating with various otherapparatus over a transmission medium. The transceiver 1510 receives asignal from the one or more antennas 1520, extracts information from thereceived signal, and provides the extracted information to theprocessing system 1514, specifically the reception component 1404. Inaddition, the transceiver 1510 receives information from the processingsystem 1514, specifically the transmission component 1410, and based onthe received information, generates a signal to be applied to the one ormore antennas 1520. The processing system 1514 includes a processor 1504coupled to a computer-readable medium/memory 1506. The processor 1504 isresponsible for general processing, including the execution of softwarestored on the computer-readable medium/memory 1506. The software, whenexecuted by the processor 1504, causes the processing system 1514 toperform the various functions described supra for any particularapparatus. The computer-readable medium/memory 1506 may also be used forstoring data that is manipulated by the processor 1504 when executingsoftware. The processing system 1514 further includes at least one ofthe components 1404, 1406, 1408, 1410. The components may be softwarecomponents running in the processor 1504, resident/stored in thecomputer readable medium/memory 1506, one or more hardware componentscoupled to the processor 1504, or some combination thereof. Theprocessing system 1514 may be a component of the eNB 310 and may includethe memory 376 and/or at least one of the TX processor 316, the RXprocessor 370, and the controller/processor 375.

In one configuration, the apparatus 1402/1402′ for wirelesscommunication includes means for receiving a plurality of combinedsignals. Each combined signal may be on a tone of a plurality of tones.Each combined signal may include a first symbol of a first plurality ofsymbols from a first UE and a second symbol of a second plurality ofsymbols from a second UE. The first plurality of symbols may include atleast one first pilot symbol and at least one first data symbol. Thesecond plurality of symbols may include at least one second pilot symboland at least one second data symbol. Each of the at least one firstpilot symbol may be on a tone that carries one of the at least onesecond data symbol. The apparatus may include means for determining afirst pilot signal on a first tone of the plurality of tones. The firsttone may carry a respective one of the at least one first pilot symboland a respective one of the at least one second data symbol. The firstpilot signal may be determined based on a channel element associatedwith the first tone and the respective one of the at least one firstpilot symbol on the first tone. The apparatus may include means forgenerating an interference-reduced signal for the first tone bycanceling the determined first pilot signal from a first combined signalon the first tone. In another configuration, the apparatus may includemeans for determining a second pilot signal on a second tone of theplurality of tones. The second tone may carry a respective one of the atleast one second pilot symbol and a respective one of the at least onefirst data symbol. The second pilot signal may be determined based on asecond channel element associated with the second tone and therespective one of the at least one second pilot symbol on the secondtone. The apparatus may include means for generating a secondinterference-reduced signal for the second tone by canceling thedetermined second pilot signal from a second combined signal on thesecond tone. In an aspect, a first set of periodic pilot signals fromthe first UE and a second set of periodic pilot signals from the secondUE are shifted by a cyclic shift. In another aspect, the apparatus mayinclude means for providing a cyclic shift to the first UE (e.g., a businterface, a transmitter, and/or transceiver). In another configuration,the apparatus may include means for deinterleaving the plurality ofcombined signals to determine a first set of pilot signals from thefirst UE, first and second code blocks from the first UE, a second setof pilot signals from the second UE, and third and fourth code blocksfrom the second UE. In an aspect, the first set of pilot signals maycorrespond to a first number tones. The first number tones may be equalto half a second number of tones in the third code block. In anotheraspect, the first set of pilot signals from the first UE may overlapwith the third code block from the second UE, and the second set ofpilot signals from the second UE may overlap with the second code blockfrom the first UE. In another configuration, the apparatus may includemeans for performing successive decoding after deinterleaving theplurality of combined signals. In another configuration, the means forperforming successive decoding may be configured to decode the thirdcode block by canceling the first set of pilot signals from the thirdcode block, to decode the first code block by canceling the third codeblock from the first code block, to decode the fourth code block bycanceling the first code block from the fourth code block, and to decodethe second code block by canceling the fourth code block from the secondcode block. The aforementioned means may be one or more of theaforementioned components of the apparatus 1402 and/or the processingsystem 1514 of the apparatus 1402′ configured to perform the functionsrecited by the aforementioned means. As described supra, the processingsystem 1514 may include the TX Processor 316, the RX Processor 370, andthe controller/processor 375. As such, in one configuration, theaforementioned means may be the TX Processor 316, the RX Processor 370,and the controller/processor 375 configured to perform the functionsrecited by the aforementioned means.

FIG. 16 is a conceptual data flow diagram 1600 illustrating the dataflow between different means/components in an exemplary apparatus 1602.The apparatus may be a UE. The apparatus includes a reception component1604, a modulation component 1606, an interleaver component 1608, and atransmission component 1610. A modulation component 1606 may beconfigured to map information (e.g., data and pilot information) ontodata symbols or pilot symbols using QPSK, QAM, or other modulationtechniques. The interleaver component 1608 may be configured to map, ata first UE, a first set of pilot symbols and a first set of data symbolsto a plurality of tones. Each pilot symbol in the first set of pilotsymbols may be mapped on a tone that is used by a second UE to carry adata symbol. The transmission component 1610 may be configured toprovide the mapped first set of pilot symbols and the mapped first setof data symbols for transmission over the plurality of tones. In anaspect, a data symbol in the first set of data symbols is mapped on atone that is used by the second UE to carry a pilot symbol. In anotheraspect, the first set of pilot symbols may be transmitted on tonesshifted by a cyclic shift from a second set of pilot symbols that isconcurrently transmitted by the second UE. In another configuration, thereception component 1604 may be configured to receive the cyclic shiftfor staggering the first set of pilot symbols from a base station. Inanother aspect, the cyclic shift for staggering the first set of pilotsymbols may be randomly selected from a set of cyclic shift values basedon an identifier associated with the first UE. In another aspect, thefirst set of data symbols may be associated with a same code block.

The apparatus may include additional components that perform each of theblocks of the algorithm in the aforementioned flowcharts of FIG. 13. Assuch, each block in the aforementioned flowcharts of FIG. 13 may beperformed by a component and the apparatus may include one or more ofthose components. The components may be one or more hardware componentsspecifically configured to carry out the stated processes/algorithm,implemented by a processor configured to perform the statedprocesses/algorithm, stored within a computer-readable medium forimplementation by a processor, or some combination thereof.

FIG. 17 is a diagram 1700 illustrating an example of a hardwareimplementation for an apparatus 1602′ employing a processing system1714. The processing system 1714 may be implemented with a busarchitecture, represented generally by the bus 1724. The bus 1724 mayinclude any number of interconnecting buses and bridges depending on thespecific application of the processing system 1714 and the overalldesign constraints. The bus 1724 links together various circuitsincluding one or more processors and/or hardware components, representedby the processor 1704, the components 1604, 1606, 1608, 1610 and thecomputer-readable medium/memory 1706. The bus 1724 may also link variousother circuits such as timing sources, peripherals, voltage regulators,and power management circuits, which are well known in the art, andtherefore, will not be described any further.

The processing system 1714 may be coupled to a transceiver 1710. Thetransceiver 1710 is coupled to one or more antennas 1720. Thetransceiver 1710 provides a means for communicating with various otherapparatus over a transmission medium. The transceiver 1710 receives asignal from the one or more antennas 1720, extracts information from thereceived signal, and provides the extracted information to theprocessing system 1714, specifically the reception component 1604. Inaddition, the transceiver 1710 receives information from the processingsystem 1714, specifically the transmission component 1610, and based onthe received information, generates a signal to be applied to the one ormore antennas 1720. The processing system 1714 includes a processor 1704coupled to a computer-readable medium/memory 1706. The processor 1704 isresponsible for general processing, including the execution of softwarestored on the computer-readable medium/memory 1706. The software, whenexecuted by the processor 1704, causes the processing system 1714 toperform the various functions described supra for any particularapparatus. The computer-readable medium/memory 1706 may also be used forstoring data that is manipulated by the processor 1704 when executingsoftware. The processing system 1714 further includes at least one ofthe components 1604, 1606, 1608, 1610. The components may be softwarecomponents running in the processor 1704, resident/stored in thecomputer readable medium/memory 1706, one or more hardware componentscoupled to the processor 1704, or some combination thereof. Theprocessing system 1714 may be a component of the UE 350 and may includethe memory 360 and/or at least one of the TX processor 368, the RXprocessor 356, and the controller/processor 359.

In one configuration, the apparatus 1602/1602′ for wirelesscommunication includes means for mapping, at a first UE, a first set ofpilot symbols and a first set of data symbols to a plurality of tones.Each pilot symbol in the first set of pilot symbols may be mapped on atone that is used by a second UE to carry a data symbol. The apparatusmay include means for providing the mapped first set of pilot symbolsand the mapped first set of data symbols for transmission over theplurality of tones. In an aspect, a data symbol in the first set of datasymbols is mapped on a tone that is used by the second UE to carry apilot symbol. In another aspect, the first set of pilot symbols may betransmitted on tones shifted by a cyclic shift from a second set ofpilot symbols that is concurrently transmitted by the second UE. Inanother configuration, the apparatus may include means for receiving thecyclic shift for staggering the first set of pilot symbols from a basestation. In another aspect, the cyclic shift for staggering the firstset of pilot symbols may be randomly selected from a set of cyclic shiftvalues based on an identifier associated with the first UE. In anotheraspect, the first set of data symbols may be associated with a same codeblock.

The aforementioned means may be one or more of the aforementionedcomponents of the apparatus 1602 and/or the processing system 1714 ofthe apparatus 1602′ configured to perform the functions recited by theaforementioned means. As described supra, the processing system 1714 mayinclude the TX Processor 368, the RX Processor 356, and thecontroller/processor 359. As such, in one configuration, theaforementioned means may be the TX Processor 368, the RX Processor 356,and the controller/processor 359 configured to perform the functionsrecited by the aforementioned means.

It is understood that the specific order or hierarchy of blocks in theprocesses/flowcharts disclosed is an illustration of exemplaryapproaches. Based upon design preferences, it is understood that thespecific order or hierarchy of blocks in the processes/flowcharts may berearranged. Further, some blocks may be combined or omitted. Theaccompanying method claims present elements of the various blocks in asample order, and are not meant to be limited to the specific order orhierarchy presented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” The word “exemplary” is used hereinto mean “serving as an example, instance, or illustration.” Any aspectdescribed herein as “exemplary” is not necessarily to be construed aspreferred or advantageous over other aspects. Unless specifically statedotherwise, the term “some” refers to one or more. Combinations such as“at least one of A, B, or C,” “at least one of A, B, and C,” and “A, B,C, or any combination thereof” include any combination of A, B, and/orC, and may include multiples of A, multiples of B, or multiples of C.Specifically, combinations such as “at least one of A, B, or C,” “atleast one of A, B, and C,” and “A, B, C, or any combination thereof” maybe A only, B only, C only, A and B, A and C, B and C, or A and B and C,where any such combinations may contain one or more member or members ofA, B, or C. All structural and functional equivalents to the elements ofthe various aspects described throughout this disclosure that are knownor later come to be known to those of ordinary skill in the art areexpressly incorporated herein by reference and are intended to beencompassed by the claims. Moreover, nothing disclosed herein isintended to be dedicated to the public regardless of whether suchdisclosure is explicitly recited in the claims. No claim element is tobe construed as a means plus function under the provisions of 35 U.S.C.§112(f) unless the element is expressly recited using the phrase “meansfor.”

What is claimed is:
 1. An apparatus for wireless communication,comprising: a processing system configured to: receive a plurality ofcombined signals, each combined signal being on a tone of a plurality oftones, each combined signal comprising a first symbol of a firstplurality of symbols from a first user equipment (UE) and a secondsymbol of a second plurality of symbols from a second UE, the firstplurality of symbols including at least one first pilot symbol and atleast one first data symbol, the second plurality of symbols includingat least one second pilot symbol and at least one second data symbol,each of the at least one first pilot symbol being on a tone that carriesone of the at least one second data symbol; determine a first pilotsignal on a first tone of the plurality of tones, the first tonecarrying a respective one of the at least one first pilot symbol and arespective one of the at least one second data symbol, the first pilotsignal being determined based on a channel element associated with thefirst tone and the respective one of the at least one first pilot symbolon the first tone; and generate an interference-reduced signal for thefirst tone by canceling the determined first pilot signal from a firstcombined signal on the first tone.
 2. The apparatus of claim 1, whereinthe processing system is further configured to: determine a second pilotsignal on a second tone of the plurality of tones, the second tonecarrying a respective one of the at least one second pilot symbol and arespective one of the at least one first data symbol, the second pilotsignal being determined based on a second channel element associatedwith the second tone and the respective one of the at least one secondpilot symbol on the second tone; and generate a secondinterference-reduced signal for the second tone by canceling thedetermined second pilot signal from a second combined signal on thesecond tone.
 3. The apparatus of claim 1, wherein a first set ofperiodic pilot signals from the first UE and a second set of periodicpilot signals from the second UE are shifted by a cyclic shift.
 4. Theapparatus of claim 1, wherein the processing system is furtherconfigured to provide a cyclic shift to the first UE.
 5. The apparatusof claim 1, wherein the processing system is configured to de-interleavethe plurality of combined signals to determine a first set of pilotsignals from the first UE, first and second code blocks from the firstUE, a second set of pilot signals from the second UE, and third andfourth code blocks from the second UE.
 6. The apparatus of claim 5,wherein the first set of pilot signals corresponds to a first numbertones, the first number tones being equal to half a second number oftones in the third code block.
 7. The apparatus of claim 5, wherein thefirst set of pilot signals from the first UE overlaps with the thirdcode block from the second UE, and the second set of pilot signals fromthe second UE overlaps with the second code block from the first UE. 8.The apparatus of claim 5, wherein the processing system is furtherconfigured to perform successive decoding after de-interleaving theplurality of combined signals.
 9. The apparatus of claim 8, wherein theprocessing system is configured to perform successive decoding by:decoding the third code block by canceling the first set of pilotsignals from the third code block; decoding the first code block bycanceling the third code block from the first code block; decoding thefourth code block by canceling the first code block from the fourth codeblock; and decoding the second code block by canceling the fourth codeblock from the second code block.
 10. An apparatus for wirelesscommunication, comprising: a processing system configured to: map, at afirst user equipment (UE), a first set of pilot symbols and a first setof data symbols to a plurality of tones, each pilot symbol in the firstset of pilot symbols being mapped on a tone that is used by a second UEto carry a data symbol; and provide the mapped first set of pilotsymbols and the mapped first set of data symbols for transmission overthe plurality of tones.
 11. The apparatus of claim 10, wherein a datasymbol in the first set of data symbols is mapped on a tone that is usedby the second UE to carry a pilot symbol.
 12. The apparatus of claim 10,wherein the first set of pilot symbols are transmitted on tones shiftedby a cyclic shift from a second set of pilot symbols that isconcurrently transmitted by the second UE.
 13. The apparatus of claim12, wherein the processing system is further configured to receive thecyclic shift for staggering the first set of pilot symbols from a basestation.
 14. The apparatus of claim 12, wherein the cyclic shift forstaggering the first set of pilot symbols is randomly selected from aset of cyclic shift values based on an identifier associated with thefirst UE.
 15. The apparatus of claim 10, wherein the first set of datasymbols is associated with a same code block.
 16. A method for wirelesscommunication, comprising: receiving a plurality of combined signals,each combined signal being on a tone of a plurality of tones, eachcombined signal comprising a first symbol of a first plurality ofsymbols from a first user equipment (UE) and a second symbol of a secondplurality of symbols from a second UE, the first plurality of symbolsincluding at least one first pilot symbol and at least one first datasymbol, the second plurality of symbols including at least one secondpilot symbol and at least one second data symbol, each of the at leastone first pilot symbol being on a tone that carries one of the at leastone second data symbol; determining a first pilot signal on a first toneof the plurality of tones, the first tone carrying a respective one ofthe at least one first pilot symbol and a respective one of the at leastone second data symbol, the first pilot signal being determined based ona channel element associated with the first tone and the respective oneof the at least one first pilot symbol on the first tone; and generatingan interference-reduced signal for the first tone by canceling thedetermined first pilot signal from a first combined signal on the firsttone.
 17. The method of claim 16, further comprising: determining asecond pilot signal on a second tone of the plurality of tones, thesecond tone carrying a respective one of the at least one second pilotsymbol and a respective one of the at least one first data symbol, thesecond pilot signal being determined based on a second channel elementassociated with the second tone and the respective one of the at leastone second pilot symbol on the second tone; and generating a secondinterference-reduced signal for the second tone by canceling thedetermined second pilot signal from a second combined signal on thesecond tone.
 18. The method of claim 16, wherein a first set of periodicpilot signals from the first UE and a second set of periodic pilotsignals from the second UE are shifted by a cyclic shift.
 19. The methodof claim 16, further comprising providing a cyclic shift to the firstUE.
 20. The method of claim 16, further comprising de-interleaving theplurality of combined signals to determine a first set of pilot signalsfrom the first UE, first and second code blocks from the first UE, asecond set of pilot signals from the second UE, and third and fourthcode blocks from the second UE.
 21. The method of claim 20, wherein thefirst set of pilot signals corresponds to a first number tones, thefirst number tones being equal to half a second number of tones in thethird code block.
 22. The method of claim 20, wherein the first set ofpilot signals from the first UE overlaps with the third code block fromthe second UE, and the second set of pilot signals from the second UEoverlaps with the second code block from the first UE.
 23. The method ofclaim 20, further comprising performing successive decoding afterde-interleaving the plurality of combined signals.
 24. The method ofclaim 23, wherein the successive decoding comprises: decoding the thirdcode block by canceling the first set of pilot signals from the thirdcode block; decoding the first code block by canceling the third codeblock from the first code block; decoding the fourth code block bycanceling the first code block from the fourth code block; and decodingthe second code block by canceling the fourth code block from the secondcode block.
 25. A method for wireless communication, comprising:mapping, at a first user equipment (UE), a first set of pilot symbolsand a first set of data symbols to a plurality of tones, each pilotsymbol in the first set of pilot symbols being mapped on a tone that isused by a second UE to carry a data symbol; and providing the mappedfirst set of pilot symbols and the mapped first set of data symbols fortransmission over the plurality of tones.
 26. The method of claim 25,wherein a data symbol in the first set of data symbols is mapped on atone that is used by the second UE to carry a pilot symbol.
 27. Themethod of claim 25, wherein the first set of pilot symbols aretransmitted on tones shifted by a cyclic shift from a second set ofpilot symbols that is concurrently transmitted by the second UE.
 28. Themethod of claim 27, further comprising receiving the cyclic shift forstaggering the first set of pilot symbols from a base station.